The Parallella platform is based on the Epiphany multicore chips
developed by Adapteva over the last 4 years and field tested since May
2011. The Epiphany chips consists of a scalable array of simple RISC
processors programmable in C/C++ connected together with a fast on
chip network within a single shared memory architecture.

My understanding of how this kind of hardware works is that the mini-cores will only prove particularly useful for parallel algorithms (remember that go optionally handles parallelism _through_ concurrency, but doesn't address parallelism directly). Non-identical concurrent tasks, such as what goroutines are often employed for, may not be viable to run on anything but the primary ARM cores ('communicating' and 'sequential' both directly hinder parallelization). Sharing memory by communicating (e.g. channels) may also not be viable except on the primary ARM cores. That said, using cgo to offload truly parallel problems, such as matrix multiplication, would be quite beneficial.

Looks like they have correctly identified the issue: somebody will
need to port libffi to support Epiphany. This isn't something I have
any time to work on myself, though I'd be happy to try to answer
questions.

Note that libffi is a separate library that the gccgo Go library uses.
libffi has nothing to do with Go.